A wide range of devices for conveyor edge product containment and control are known, although typically, these devices generally use mechanical means and contact with the conveyor to prevent side discharge of the product off of the conveyor edge. On a typical papermaking machine, the paper pulp slurry is delivered onto a conveyor from an extruder or what is commonly known as a headbox. As the paper pulp slurry is extruded onto the continuous conveyor it contains a large amount of liquid, mainly water that will be gradually removed via drainage or dewatering elements positioned under the screen conveyor. The paper pulp slurry's high water content and/or combined basis weight at the extruder or headbox is typically difficult to deliver from the headbox to the conveyor and prevent side discharge and maintain slurry profile as the product tends to expand and spread as it is extruded onto the conveyor.
There are two basic types of conveyor containment devices that have been utilized alongside the edge of the conveyor to prevent the slurry from running off the edge of the conveyor as the liquids are removed from the paper pulp slurry and becoming dry enough to not need further containment and allow the product to be transferred further down the machine and ultimately lifted off of the continuous conveyor.
The first type of containment devices utilize mechanical means of physically lifting the edge, or curling, the conveyor, while the second method of containment is to use an apparatus placed over the top of the conveyor in an attempt to dam the slurry from premature spread or leaking off the conveyor. Most examples of this prior art make contact with or is set so close to the top surface of the conveyor as to be in contact or virtually contacting and uses an elastomeric or mechanical seal, typically rubber. The inherent problems associated with both types of devices are numerous.
The paper pulp slurry conveyor is typically constructed of monofilament or plastic fibers which are very flexible but also quite vulnerable to damage and/or wear, Newcombe U.S. Pat. No. 4,738,751, Beran et al. U.S. Pat. No. 4,968,387 and Peterson U.S. Pat. No. 5,296,101 show us typical edge lifting devices that make contact with the bottom of the conveyor and curl the edge of said conveyor to stop the pulp slurry from leaving the edge of the conveyor. This is a simple method of stopping the flow from leaving the conveyor and has been used since the introduction of modern paper making machines. The associated problems experienced by users of this method are conveyor wear due to lifting the edge, damage to the edge curler or lifting device or conveyor when the conveyor travels horizontally to one side of the machine or the other, and most importantly, waves and disruption created as the pulp slurry spreads and makes initial contact with the lifted edge of the conveyor that cannot be positioned or placed in a proximity close enough to the headbox or extruder because of the curl or lifting of the edge of the conveyor itself. As the pressurized paper pulp slurry of the modern paper and pulp machine is delivered to the conveyor it expands and/or spreads to be ultimately bounced or reflected off the lifted edge of said conveyor.
Beran et al. U.S. Pat. No. 4,968,387 and Peterson U.S. Pat. No. 5,296,101 show an edge curling device used in conjunction with an elastomeric or rubber seal deckling device positioned over the wire or conveyor. Said devices utilize the edge curler as the means to stop the pulp slurry from premature spread and leaving the conveyor and the addition of the elastomeric deckling device over the conveyor attempts to mitigate the associated waves and disruption to the paper slurry caused by the edge lifter. In actuality the elastomeric deckling device in conjunction with the edge curler is difficult to adjust and easily creates a pinch point of the conveyor, creating an additional wear point on the conveyor. Also, the elastomeric device intends the operator to allow an amount of the pulp slurry past and onto the lifted conveyor edge which effectively creates a separation of the slurry changing not only the fiber orientation but adversely affecting the overall formation of the paper product when compared to the area of the sheet adjacent to the device and edge lifter as well as agitating or irritating the fiber slurry and not allowing it to set as it moves along the lifters length.
As one knowledgeable to the prior art can easily determine, containment devices which lift the edge of the conveyor, as shown by Newcombe U.S. Pat. No. 4,738,751, Beran et al. U.S. Pat. No. 5,284,551, Peterson U.S. Pat. No. 5,296,101 and Reed U.S. Pat. No. 8,236,139 B1 apply constant pressure and wear on the bottom surface edge of the conveyor as they attempt to prevent slurry discharge off the side by curling or lifting the side of the conveyor up. These conveyor edge lifting devices cannot be used in close proximity to the extruder or headbox area because of the need to be positioned under the conveyor and this gap or transition result in reflective waves in the paper pulp slurry, affecting product fiber orientation, side leakage and poor product edge formation.
Reed U.S. Pat. No. 8,236,139 shows us a design modification to the edge lifter where the device proposes to dewater the paper slurry as it rides along the apparatus. This may address the dryness of the paper slurry but does nothing about the profile control of said paper product and in all likelihood the attendant dewatering zones in the edge lifter will create additional sheet edge turbulence and reflective waves as well as wet streaks in the pulp slurry at the area at the bottom edge of the lifting device under the conveyor before the dewatering zones begin. Reeds device inherently increases wear on the conveyor edge because of the vacuum created as the conveyor moves across the inventors proposed dewatering areas.
Moody et al. U.S. Pat. No. 3,607,624 shows us an embodiment of a typical elastomeric deckling device using an elastomeric seal strip at its bottom edge, the referred device's proximity to and inherently close contact with the conveyor must be fashioned of softer, more wear prone, material than the conveyor itself. Thus the seal wears and changes characteristics while in operation, making their use troublesome and requiring constant adjustment for exhibited wear which ultimately results in the paper pulp slurry leaking out the sides, damage to the conveyor and/or turbulence created by the uneven wear of the seal. Moody et al and other embodiments of this type of device typically use a metal, rigid main body suspended over the wire or conveyor with an unlike elastomeric or rubber strip fixed to the bottom edge of the metal device body. While being, as exhibited in most prior art, heavy, cumbersome and hard to adjust, the unlike seal material expands and contracts with thermal activity and makes the device that much harder to control or adjust as the machine heats or cools.
The elastomeric seal inherently must be set within very close tolerance, effectively in contact with the conveyor, resulting in subsequent wear of the conveyor surface as the conveyor is in constant directional motion and the under conveyor dewatering devices or elements create uneven pressure points or pulsing that also contributes to the wear of the critical set point of said elastomeric seal, typically soft rubber or vinyl.
These associated devices with their contact or mechanical sealing apparatus exhibit many of the same problems such as side leakage, excessive wear of seal and conveyor, poor product edge formation, and reflective waves into the slurry. Ultimately the edge lifting devices, because they must be placed a distance from the headbox downstream allow the paper slurry to spread and then bounce or reflect back into the slurry with a wave or disturbance. Even when a deckling device placed upstream of the edge lifter, no matter the distance downstream along the conveyor, at the transition point from deckling device to curler, a resulting wave or sheet edge disturbance is experienced.
Baluha U.S. Pat. No. 5,045,154 proposes a device where fluid is delivered to an area behind a front sealing lip and contained between a front sealing edge and a back containment edge embodied in a vertically oriented body. The device's design, when adequate water seal is not maintained, allows excess paper slurry to enter into the area between the front and back containment edges and potentially dam or plug this slot or area. The nozzles integrated inside the area between the front and back containment edges protrude down inside the slot area and when said slurry is allowed to enter this area it coagulates or builds up on the protruding nozzles, increasing the likelihood of plugging the slot area. Once the slot area builds up or plugs the user has no recourse for cleaning this area except to remove the device from the machine, which in all likelihood will result in stoppage of said machine and loss of production. Also the front sealing face of this design is incorporated into the overall design and if damaged or worn the entire device must be replaced. The vertical orientation of the unit makes the apparatus susceptible to horizontal pressures and the verticality of the devices elastomeric components when subjected to temperature changes and lack of integrated horizontal structure or design tends towards longitudinal bowing which can contribute to waves or disruption in the sheet edge product.
Laari U.S. Pat. No. 7,494,570 B2 shows us a device incorporating not one but two slot areas prone to stock accumulation and plugging. Baluha U.S. Pat. No. 5,045,154 and Laari U.S. Pat. No. 7,494,570 present devices that include the seal lips or faces into the unit design and do not have means for change without modifying or changing the overall apparatus.
The present disclosure generally pertains to the improved design and application of an improved conveyor product containment device wherein the front seal face is independent of the main body of the device, where the water delivery manifold is vertically adjustable to minimize water use and maximize the low pressure cohesive, non-contacting seal between the bottom edge of the front seal face and the conveyor. The vertical adjustability of the water manifold in relation to the front seal lip that incorporates a wider flat width at the bottom edge to maximize fluid cohesion with the seal lip reduces the amount of fluid required to maintain a positive, non-wearing seal with the conveyor and increases the gap between the bottom edge of the front seal and the top of the conveyor.
The present disclosure also generally pertains to a proposed improved conveyor product containment device wherein the independent front seal face can be aligned vertically to a height appropriate for a specific product basis weight, thickness or machine condition and can be easily changed if damaged or worn independently of the main device body. The device fluid manifold can be precisely positioned vertically in relation to the independent front seal face so that the delivery of the water or device seal fluid through recessed nozzles aligned in the main body is in the optimal position for the product pulp slurry being manufactured. The device has an open lower backside so that the user can observe the fluid delivery, associated fluid seal, and also more easily check and maintain the generous gap between the front seal face and the conveyor surface. The recessed nozzles and open lower back area prevents excess or escaping pulp slurry from accumulating and provides easier access to this area for maintenance and cleaning.
The improved conveyor product containment device may be constructed of high operating temperature polyethylene or other similar elastomeric materials that resist thermal breakdown and expansion and are more suitable to today's modern, faster and higher temperature paper making machines. A proposed device that incorporates complementary dimensionally shaped components aligned in the design that gives greater balance of internal and external forces and utilizes like-size components to further enhance the device's overall dimensional and thermal stability and better resist horizontal, vertical and longitudinal forces.
A proposed improved conveyor product containment device where there is provided an elongate dimensionally stable device acting as an improved conveyor product containment device comprising an elongate rectangular main body having a top, bottom, two short elongate sides and two short ends. The device further comprises an independent front seal face that is conventionally attached to one short elongate side of the main body. Stainless steel screws or other suitable fasteners may be used. The front seal face may be vertically secured to the main body at a variably fixed height in relation to the vertically adjustable water manifold with recessed overlapping nozzles that reduce the likelihood of stock slurry from accumulating or hanging up on while they create an improved non-contacting water seal at the lower flat bottom portion of the front seal face. The front seal face can be of a variable height required for specific product thickness or basis weight, normally in direct relation to the extruder's maximum extrusion opening or product activity. The main body is typically comprised of two separate parts, a horizontally oriented top and bottom that are fastened together with stainless steel screws, but any suitable fastener may be used. The independent water manifold is located in a machined area normally centered and along the length in the bottom horizontal main body component along with an associated o-ring groove and seal positioned between the top that creates the horizontally oriented manifold seal plate. An opening or inlet in the manifold top supplies water to overlapping nozzles that are positioned along the length of the independent main body water manifold, another opening in the top is used to locate a gauge to indicate the internal fluid pressure and approximate flow to the recessed nozzles. The horizontally oriented main body is then secured to the independent vertically oriented front seal face to create an overall more stable component, more resistant to dimensional forces. The improved device design uses the vertical front seal face orientation opposite the horizontal orientation of the main body in complementary shapes and sizes to create a more dimensionally stable unit that better resists machine loads and thermal expansion and contraction of the device. The horizontal main body can be fixed to the vertical front seal face at a variable horizontal height, delivering the fluid to a variable area behind the independent front seal face as the user deems appropriate.
In a preferred embodiment, the device incorporates a stainless steel tee channel that is fixed typically with stainless steel truss head screws to the back short bottom side of the elongate main body opposite the front seal face to further increase the proposed device's overall dimensional stability and allow easy attachment of mounting hardware that will allow the vertical and horizontal positioning of the device on the paper making machine in relation to the headbox slice area or extruder opening. A stainless steel square support tube usually of similar length as the main body and tee channel, is then secured to the stainless steel tee channel using tee bolts equally spaced along the tube length to further increase the overall unit stability and allowing the attachment of mounting hardware to a short collar of square tubing that slides over the outer dimension of the elongate square support tube. A short round pin is attached parallel to the collar so that vertically and horizontally adjustable mounting hardware can easily be attached to the device by sliding a corresponding round sleeve extender over the pin and securing the two pieces normally with a spring loaded locking pin or similar method. This allows the device to be mounted securely and yet easily removed from the machine for access or maintenance.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.